Chinese security personnel have swamped Beijing's Tiananmen Square on the 25th anniversary of the Beijing massacre.

Foreign journalists were ushered away from the square and passers-by were searched and had their papers checked.

In recent weeks, the authorities have detained dozens of activists to ensure their silence on the anniversary.

The 1989 protesters wanted political reform, but the crackdown was ordered after hardliners won a power struggle within the ruling Communist Party.

The authorities classify the 1989 protests as counter-revolutionary riots and hold no memorial.

In Hong Kong, however, thousands have gathered in a central park to participate in a Tiananmen remembrance rally.

Activist groups in Taiwan also marked the anniversary by erecting a huge image of Tiananmen Square during the crackdown.

Paramilitary police joined regular forces to control the square, in the centre of Beijing

But Chinese tourists thronged the square as usual, and seemed to notice little out of the ordinary

Both the Taiwanese and Japanese governments urged Beijing to use the memory of the protests to improve its attitude to human rights.

In the weeks before this year's anniversary, the Chinese authorities have detained lawyers, journalists and activists.

Rights group Amnesty International said in a statement that 66 people had been detained, questioned or had gone missing.

In a White House statement, the US called on the Chinese authorities "to account for those killed, detained or missing in connection with events surrounding 4 June 1989".

Internet search terms related to the 1989 massacre and the protests have been blocked, and access on Google has reportedly been restricted.

Relatives of those killed in the massacre were allowed to visit the graves of their loved ones under police guard.

Thousands gathered for a vigil in Hong Kong, which retains civil liberties not seen in mainland China

Organisers said they were expecting record numbers to attend

The relatives, some of whom campaign for the massacre to be commemorated as part of the Tiananmen Mothers group, told the BBC plain-clothes police were guarding the graveyard and they were told not to talk to the media.

Nobel Peace Prize-nominated rights activist Hu Jia, currently under house arrest, said he regretted not being able to take part in commemorations.

"But it warms my heart that those events and those sacrifices have not been forgotten after 25 years," he told the Associated Press.

The protests were the biggest rally against communist rule since the People's Republic was founded in 1949.

Hundreds of thousands called for democratic reforms in a peaceful demonstration largely focused on a gathering in Tiananmen Square.

After six weeks of protests, the authorities responded on 4 June 1989 with a massacre of hundreds in the streets of Beijing.

Chinese media remain largely quiet on the 25th anniversary of the Tiananmen massacre, while Hong Kong and Taiwanese papers give prominent coverage to the event.

Security has been tightened in Tiananmen Square

Hundreds of thousands called for democratic reforms in a peaceful demonstration largely focused on a gathering in Tiananmen Square in the summer of 1989.

Security forces cracked down on the six-week protests on 4 June 1989, killing hundreds in the streets of Beijing. The authorities classify the 1989 protests as counter-revolutionary riots and hold no memorial.

Some Chinese papers discuss the controversial topic of democracy, but without making any direct comment on the Tiananmen Square incident.

A headline in the Global Times' editorial reads: "25 years on, society firmer about its path."

The editorial, which is only available in print and e-paper format, criticises media outlets in the US and Europe for "ramping up" reports on "China's crackdown on illegal activities in the public sphere" leading up to the anniversary.

"China has shielded relevant information in a bid to wield a positive influence on the smooth development of reform and opening-upâ€¦ Chinese society has never forgotten the incident 25 years ago but not talking about it indicates the attitude of society," it says.

Adding that the "Chinese society still remembers how poor we were 25 years ago", it quotes examples of Ukraine and Thailand to caution against the "preaching and appeals from the West".

"We will not follow the steps of the West. Even those who are captivated by Western ideology are alert to the possibility of the country sinking into turbulence," it warns.

Echoing similar sentiments, an article in the China Daily praises "socialist democracy with Chinese characteristics".

Making no mention of the incident, Liu Guijun, a researcher with the Communist Party Central Committee's Literature Research office, writes that "China's democracy is people's democracy under the leadership of the party".

"Therefore, if China adheres to the development path it has chosen, it can establish itself as a successful institutional system different from those followed by Western countries," he adds.

'Brutal crackdown'
Meanwhile, both Hong Kong and Taiwanese news outlets quote China's Foreign Ministry spokesperson Hong Lei as saying that the Chinese government had long ago reached "the conclusion about the political turmoil at the end of the 1980s".

However, the foreign ministry's press conference website is not carrying Mr Hong's remarks.

Hong Kong media outlets also report that support for the 1989 student protests has dropped, although a majority of Hong Kong residents still believe that the central government was wrong in suppressing the protests.

According to a survey conducted by Hong Kong University's Public Opinion Programme, only 48% of the respondents agreed that "the Beijing students did the right thing", in contrast with 54% a year ago.

The South China Morning Post expects "tens of thousands of Hong Kongers" to attend the candlelight vigil on Wednesday as people still remember the "tragedy of the brutal crackdown" and "younger people have taken up the candles from the older generation".

In Taiwan, experts tell the Apple Daily that China's suppression of dissenting voices is stronger than in the past.

Media outlets also report that President Ma Yingjeou has urged the mainland to "think hard about the significance of the Tiananmen massacre" and to turn the "historic scar" into energy to "push forward real reforms of the country's political and social systems".

A report in the Central News Agency observes that the atmosphere is tense in Beijing and that there are "more armed police than tourists in Tiananmen Square" on Wednesday.

"The country's system is reminding the people not to create trouble, but the public are awakening too. Keeping silent does not mean they do not know [about the incident]â€¦ a big country needs to have the courage to face up to the past before it can become a strong country," it adds.